Ecology

Ecosystems are defined by a web, community, or network of individuals that arrange into a self-organized and complex hierarchy of pattern and process(SONY Vaio VGN-CR13G/B battery). Ecosystems create a biophysical feedback between living (biotic) and nonliving (abiotic) components of an environment that generates and regulates thebiogeochemical cycles of the planet(SONY Vaio VGN-CR13G/L battery). Ecosystems provide goods and services that sustain human societies and general well-being. Ecosystems are sustained bybiodiversity within them. Biodiversity is the full-scale of life and its processes, including genes(SONY Vaio VGN-CR13G/W battery), species and ecosystems forming lineages that integrate into a complex and regenerative spatial arrangement of types, forms, and interactions.

Ecology is a sub-discipline of biology, the study of life. The word "ecology" ("oekologie") was coined in 1866 by the German scientist Ernst Haeckel(1834–1919) (SONY Vaio VGN-CR13G/P battery). Haeckel was a zoologist, artist, writer, and later in life a professor of comparative anatomy. Ancient philosophers of Greece, including Hippocrates and Aristotle, were among the earliest to record notes and observations on the natural history of plants and animals(SONY Vaio VGN-CR13G/R battery); the early rudiments of modern ecology. Modern ecology mostly branched out of natural history science that flourished in the late 19th century. Charles Darwin's evolutionary treatise and the concept of adaptation as it was introduced in 1859 is a pivotal cornerstone in modern ecological theory(SONY Vaio VGN-CR13T/L battery).

Ecology is not synonymous with environment, environmentalism, natural history or environmental science. Ecology is closely related to the biological disciplines of physiology, evolution, genetics and behavior(SONY Vaio VGN-CR13T/P battery). An understanding of how biodiversity affects ecological function is an important focus area in ecological studies. Ecosystems sustain every life-supporting function on the planet, including climate regulation(SONY Vaio VGN-CR13T/R battery), water filtration, soil formation (pedogenesis), food, fibers, medicines, erosion control, and many other natural features of historical, spiritual or scientific value(SONY Vaio VGN-CR13T/W battery).

Ecologists seek to explain:

life processes and adaptations

distribution and abundance of organisms

the movement of materials and energy through living communities

the successional development of ecosystems, and

the abundance and distribution of biodiversity in context of the environment(SONY Vaio VGN-CR15/B battery).

There are many practical applications of ecology in conservation biology, wetland management, natural resource management(agriculture, forestry, fisheries), city planning (urban ecology), community health, economics(SONY Vaio VGN-CR190 battery), basic & applied science and it provides a conceptual framework for understanding and researching human social interaction (human ecology).

Levels of organization and study

Scale and complexity

Ecosystems are forever confronted with a range of natural environmental fluctuations that vary transiently in magnitude through space and time(SONY Vaio VGN-CR190E/L battery). It can take thousands of years for ecological processes to mature; the life-span of a tree, for example, can encompass differentsuccessional stages. The ecological process is extended even further through time as trees die, decay and provide habitat as nurse logsorcoarse woody debris(SONY Vaio VGN-CR190E/P battery). The area of an ecosystem can vary greatly from tiny to vast. A single tree is of little consequence to the classification of a forest ecosystem, but critically relevant to the smaller organisms living in and on it. Several generations of an aphid population can exist over the lifespan of a single leaf(SONY Vaio VGN-CR190E/R battery). Each of those aphids, in turn, support diverse bacterial communities. Fine scale structure of aphid populations can be constrained by top-down influences of tree growth that is related to site specific variables, such as soil type, moisture content, slope of the land(SONY Vaio VGN-CR190E/W battery), and forest canopy closure. Likewise, finer scale dynamics operating in the aphid populations can impart bottom-up influence on tree growth rates. The scale of ecological dynamics can operate as a closed island with respect to local site variables(SONY Vaio VGN-CR21/B battery), such as aphids migrating on a tree, while at the same time remain open with regard to broader scale influences, such as atmosphere or climate. Hence, ecologists have devised means of hierarchically classifying ecosystems by analyzing data collected from finer scale units, such as vegetation associations(SONY Vaio VGN-CR21E/L battery), climate, and soil types, and integrate this information to identify larger emergent patterns of uniform organization and processes that operate on regional, local, and chronological scales(SONY Vaio VGN-CR21E/P battery).

There are different views on complexity and how it relates to ecology. One perspective lumps things that we do not understand into this category by virtue of the computational effort it would require to piece together the numerous interacting parts(SONY Vaio VGN-CR21E/W battery). Alternatively, complexity in life sciences can be viewed as emergent self-organized systems with multiple possible outcomes directed by random accidents of history; an extension of the first perspective. Global patterns of biological diversity are complex(SONY Vaio VGN-CR21S/L battery). This biocomplexity stems from the interplay among ecological processes that operate and influence patterns that grade into each other, such as transitional areas or ecotones that stretch across different scales. "Complexity in ecology is of at least six distinct types(SONY Vaio VGN-CR21S/P battery): spatial, temporal, structural, process, behavioral, and geometric." Small scale patterns do not necessarily explain large scale phenomena, otherwise captured in the expression 'the sum is greater than the parts'(SONY Vaio VGN-CR21S/W battery). Ecologists have identified emergent and self-organizing phenomena that operate at different environmental scales of influence, ranging from molecular to planetary, and these require different sets of scientific explanation(SONY Vaio VGN-CR21Z/N battery). Long-term ecological studies provide important track records to better understand the complexity of ecosystems over longer temporal and broader spatial scales. The International Long Term Ecological Network manages and exchanges scientific information among research sites(SONY Vaio VGN-CR21Z/R battery). The longest experiment in existence is the Park Grass Experiment that was initiated in 1856. Another example includes the Hubbard Brook study in operation since 1960.

To structure the study of ecology into a manageable framework of understanding(SONY Vaio VGN-CR220E/R battery), the biological world is conceptually organized as a nested hierarchy of organization, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species and up to the level of the biosphere. Together these hierarchical scales of life form a panarchy(SONY Vaio VGN-CR23/B battery). Ecosystems are primarily researched at three key levels of organization—organisms, populations, and communities. Ecologists study ecosystems by sampling a certain number of individuals that are representative of a population(SONY Vaio VGN-CR23/P battery). Ecosystems consist of communities interacting with each other and the environment. In ecology, communities are created by the interaction of the populations of different species in an area.

Biodiversity

Biodiversity (an abbreviation of biological diversity) describes the diversity of life from genes to ecosystems and spans every level of biological organization(SONY Vaio VGN-CR23/R battery). Biodiversity means different things to different people and there are many ways to index, measure, characterize, and represent its complex organization. Biodiversity includes species diversity, ecosystem diversity, genetic diversity and the complex processes operating at and among these respective levels(SONY Vaio VGN-CR23/L battery). Biodiversity plays an important role in ecological health as much as it does for human health. Preventing or prioritizingspecies extinctions is one way to preserve biodiversity, but populations, the genetic diversity within them and ecological processes, such as migration(SONY Vaio VGN-CR23/N battery), are being threatened on global scales and disappearing rapidly as well. Conservationpriorities and management techniques require different approaches and considerations to address the full ecological scope of biodiversity(SONY Vaio VGN-CR23/W battery). Populations and species migration, for example, are more sensitive indicators ofecosystem services that sustain and contribute natural capitaltoward the well-being of humanity. An understanding of biodiversity has practical application for ecosystem-based conservation planners as they make ecologically responsible decisions in management recommendations to consultant firms, governments and industry(Dell Latitude E5400 battery).

Niche and habitat

There are many definitions of the niche dating back to 1917, but G. Evelyn Hutchinson made conceptual advances in 1957 and introduced the most widely accepted definition: "The niche is the set of biotic and abiotic conditions in which a species is able to persist and maintain stable population sizes(Dell Latitude E6400 battery)." The ecological niche is a central concept in the ecology of organisms and is sub-divided into the fundamental and the realized niche. The fundamental niche is the set of environmental conditions under which a species is able to persist(Dell Latitude E6500 battery). The realized niche is the set of environmental plus ecological conditions under which a species persists. The Hutchisonian niche is defined more technically as an "euclidean hyperspace whose dimensions are defined as environmental variables and whose size is a function of the number of values that the environmental values may assume for which an organism has positive fitness(SONY VGP-BPS10 battery)."

The habitat of a species is a related but distinct concept that describes the environment over which a species is known to occur and the type of community that is formed as a result(SONY VGP-BPL10 battery). More specifically, "habitats can be defined as regions in environmental space that are composed of multiple dimensions, each representing a biotic or abiotic environmental variable; that is, any component or characteristic of the environment related directly (e.g. forage biomass and quality) or indirectly (e.g. elevation) to the use of a location by the animal(SONY VGP-BPS22A battery)." For example, the habitat might refer to an aquatic or terrestrial environment that can be further categorized as montane oralpine ecosystems.

Biogeographical patterns and range distributions are explained or predicted through knowledge and understanding of a species traits and niche requirements(SONY VGP-BPS22/A battery). Species have functional traits that are uniquely adapted to the ecological niche. A trait is a measurable property, phenotype, or characteristic of an organism that influences its performance. Genes play an important role in the development and expression of traits(SONY VGP-BPS18 battery). Resident species evolve traits that are fitted to their local environment. This tends to afford them a competitive advantage and discourages similarly adapted species from having an overlapping geographic range(SONY VGP-BPS22 battery). The competitive exclusion principlesuggests that two species cannot coexist indefinitely by living off the same limiting resource. When similarly adapted species are found to overlap geographically, closer inspection reveals subtle ecological differences in their habitat or dietary requirements(SONY VGP-BPS14B Battery). Lately this paradigm has been refuted because there are many examples of species that do follow exactly the same successful strategy. A familiar example being the Chiffchaff and the Willow Warbler, but also trees in a rain forest, very similar water beetles(SONY VGP-BPS14/S Battery) , algae and prairie birds can be very similar. Mathematical modelling has shown that two successful strategies are possible: being similar enough to a successful species, or being dissimilar enough(SONY VGP-BPS14/B Battery). According to the models it is the lumps of very similar species can take the classical place of the species in the competitive exclusion principle based models.

Niche construction

Organisms are subject to environmental pressures, but they are also modifiers of their habitats. The regulatory feedback between organisms and their environment can modify conditions from local (e.g., a beaver pond) to global scales (e.g., Gaia) (SONY VGP-BPS14 Battery), over time and even after death, such as decaying logs or silica skeleton deposits from marine organisms. The process and concept of ecosystem engineering has also been called niche construction. Ecosystem engineers are defined as: "...organisms that directly or indirectly modulate the availability of resources to other species(SONY VGP-BPS12 battery), by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats."

The ecosystem engineering concept has stimulated a new appreciation for the degree of influence that organisms have on the ecosystem and evolutionary process(SONY VGP-BPL12 battery). The terms niche construction are more often used in reference to the under appreciated feedback mechanism of natural selection imparting forces on the abiotic niche. An example of natural selection through ecosystem engineering occurs in the nests of social insects, including ants, bees, wasps, and termites(SONY VGP-BPL11 battery). There is an emergenthomeostasis or homeorhesis in the structure of the nest that regulates, maintains and defends the physiology of the entire colony. Termite mounds, for example, maintain a constant internal temperature through the design of air-conditioning chimneys(SONY VGP-BPS11 battery). The structure of the nests themselves are subject to the forces of natural selection. Moreover, the nest can survive over successive generations, which means that ancestors inherit both genetic material and a legacy niche that was constructed before their time(HP Pavilion DV6-1210SA battery).

Population ecology

The population is the unit of analysis in population ecology. A population consists of individuals of the same species that live, interact and migrate through the same niche and habitat. A primary law of population ecology is the Malthusian growth model. This law states that(Sony Vaio VGN-FZ battery):

"...a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."

This Malthusian premise provides the basis for formulating predictive theories and tests that follow(Sony VGP-BPS8 battery). Simplified population models usually start with four variables including death, birth, immigration, and emigration. Mathematical models are used to calculate changes in population demographics using a null model. A null model is used as a null hypothesis for statistical testing(Sony VGP-BPL9 battery). The null hypothesis states that randomprocesses create observed patterns. Alternatively the patterns differ significantly from the random model and require further explanation. Models can be mathematically complex where "(Sony VGP-BPS9 battery)...several competing hypotheses are simultaneously confronted with the data." An example of an introductory population model describes a closed population, such as on an island, where immigration and emigration does not take place(Sony VGP-BPL11 battery). In these island models the rate of population change is described by:

where N is the total number of individuals in the population, B is the number of births, D is the number of deaths, b and d are the per capita rates of birth and death respectively, and r is the per capita rate of population change(Sony VGP-BPL15 battery). This formula can be read out as the rate of change in the population (dN/dT) is equal to births minus deaths (B – D).

Using these modelling techniques, Malthus' population principle of growth was later transformed into a model known as the logistic equation(Sony VGN-FZ460E battery):

where N is the number of individuals measured as biomass density, a is the maximum per-capita rate of change, and K is the carrying capacity of the population. The formula can be read as follows: the rate of change in the population (dN/dT) is equal to growth (aN) that is limited by carrying capacity (1 – N/K) (Sony VGP-BPS11 battery). The discipline of population ecology builds upon these introductory models to further understand demographic processes in real study populations and conduct statistical tests(SONY VAIO VGN-FZ4000 Battery). The field of population ecology often uses data on life history and matrix algebrato develop projection matrices on fecundity and survivorship. This information is used for managing wildlife stocks and setting harvest quotas.

Metapopulation ecology

Populations are also studied and modeled according to the metapopulation concept(Sony VGP-BPS10 battery). The metapopulation concept was introduced in 1969: as a population of populations which go extinct locally and recolonize." Metapopulation ecology is another statistical approach that is often used in conservation research. Metapopulation research simplifies the landscape into patches of varying levels of quality(Sony VGP-BPS13 battery).

In metapopulation terminology there are emigrants (individuals that leave a patch), immigrants (individuals that move into a patch) and sites are classed either as sources or sinks. A site is a generic term that refers to places where ecologists sample populations, such as ponds or defined sampling areas in a forest( Sony VGP-BPS3 battery). Source patches are productive sites that generate a seasonal supply of juveniles that migrate to other patch locations. Sink patches are unproductive sites that only receive migrants and will go extinct unless rescued by an adjacent source patch or environmental conditions become more favorable(Sony VGP-BPS2 battery). Metapopulation models examine patch dynamics over time to answer questions about spatial and demographic ecology. The ecology of metapopulations is a dynamic process of extinction and colonization. Small patches of lower quality (i.e., sinks) are maintained or rescued by a seasonal influx of new immigrants(Sony Vaio VGN-FZ21M battery ). A dynamic metapopulation structure evolves from year to year, where some patches are sinks in dry years and become sources when conditions are more favorable. Ecologists use a mixture of computer models and field studies to explain metapopulation structure(Sony VGN-FZ150E battery).

Community ecology

Community ecology is the study of the interactions among a collection of interdependent species that cohabitate the same geographic area. An example of a study in community ecology might measure primary production in a wetland in relation to decomposition and consumption rates(Sony VGN-FZ15 battery). This requires an understanding of the community connections between plants (i.e., primary producers) and the decomposers (e.g., fungi and bacteria). or the analysis of predator-prey dynamics affecting amphibian biomass. Food webs and trophic levels are two widely employed conceptual models used to explain the linkages among species(Sony VGN-FZ15L battery).

Food webs

A food web is the archetypal ecological network. They are a type of concept map that illustrate pathways of energy flows in an ecological community, usually starting with solar energy being used by plants duringphotosynthesis(Sony Vaio VGN-FZ18M battery). As plants grow, they accumulate carbohydrates and are eaten by grazing herbivores. Step by step lines or relations are drawn until a web of life is illustrated.

There are different ecological dimensions that can be mapped to create more complicated food webs, including: species composition (type of species), richness (number of species), biomass (the dry weight of plants and animals) (Sony VGN-FZ15T battery), productivity (rates of conversion of energy and nutrients into growth), and stability (food webs over time). A food web diagram illustrating species composition shows how change in a single species can directly and indirectly influence many others(Sony VGN-FZ480E battery). Microcosm studies are used to simplify food web research into semi-isolated units such as small springs, decaying logs, and laboratory experiments using organisms that reproduce quickly, such as daphnia feeding on algae grown under controlled environments in jars of water(Sony VGN-FZ61B battery).

Principles gleaned from food web microcosm studies are used to extrapolate smaller dynamic concepts to larger systems. Food webs are limited because they are generally restricted to a specific habitat, such as a cave or a pond. The food web illustration (right) only shows a small part of the complexity connecting the aquatic system to the adjacent terrestrial land(Sony VGN-FZ31E battery). Many of these species migrate into other habitats to distribute their effects on a larger scale. In other words, food webs are incomplete, but are nonetheless a valuable tool in understanding community ecosystems.

Trophic dynamics

The Greek root of the word troph, τροφή, trophe, means food or feeding(Sony VGN-FZ340E battery). Links in food-webs primarily connect feeding relations or trophismamong species. Biodiversity within ecosystems can be organized into vertical and horizontal dimensions. The vertical dimension represents feeding relations that become further removed from the base of the food chain up toward top predators(Sony VGN-FZ180E battery). The horizontal dimension represents the abundance or biomass at each level. When the relative abundance or biomass of each functional feeding group is stacked into their respective trophic levels they naturally sort into a ‘pyramid of numbers’. Functional groups are broadly categorized as autotrophs(or primary producers), heterotrophs (or consumers) (Sony VGN-FZ18E battery), and detrivores (ordecomposers). Heterotrophs can be further sub-divided into different functional groups, including: primary consumers (strict herbivores), secondary consumers (predators that feed exclusively on herbivores) andtertiary consumers (predators that feed on a mix of herbivores and predators) (Sony VGP-BPL4 battery). Omnivores do not fit neatly into a functional category because they eat both plant and animal tissues. It has been suggested that omnivores have a greater functional influence as predators because relative to herbivores they are comparatively inefficient at grazing.

The decomposition of dead organic matter, such as leaves falling on the forest floor, turns into soils that feed plant production(Sony VGN-FZ160E battery). The total sum of the planet's soil ecosystems is called the pedosphere where a very large proportion of the Earth's biodiversity sorts into other trophic levels. Invertebrates that feed and shred larger leaves, for example, create smaller bits for smaller organisms in the feeding chain(Sony VGN-FZ15M battery). Collectively, these are the detrivores that regulate soil formation. Tree roots, fungi, bacteria, worms, ants, beetles, centipedes, spiders, mammals, birds, reptiles, amphibians and other less familiar creatures all work to create the trophic web of life in soil ecosystems(Sony Vaio VGN-FZ18G battery). As organisms feed and migrate through soils they physically displace materials, which is an important ecological process called bioturbation. Biomass of soilmicroorganismsare influenced by and feed back into the trophic dynamics of the exposed solar surface ecology(Sony VGN-FZ345E battery). Paleoecological studies of soils places the origin for bioturbation to a time before the Cambrian period. Other events, such as the evolution of trees and amphibians moving into land in the Devonian period played a significant role in the development of soils and ecological trophism(Sony VGP-BPS14 battery).

Functional trophic groups sort out hierarchically into pyramidic trophic levels because it requires specialized adaptations to become a photosynthesizer or a predator, so few organisms have the adaptations needed to combine both abilities(Sony PCGA-BP1N battery). This explains why functional adaptations to trophism (feeding) organizes different species into emergent functional groups. Trophic levels are part of the holisticor complex systems view of ecosystems. Each trophic level contains unrelated species that grouped together because they share common ecological functions(Sony PCGA-BP2E battery). Grouping functionally similar species into a trophic system gives a macroscopic image of the larger functional design.

Keystone species

A keystone species is a species that is disproportionately connected to more species in the food-web. Keystone species have lower levels of biomass in the trophic pyramid relative to the importance of their role(Sony VGN-FZ11S battery). The many connections that a keystone species holds means that it maintains the organization and structure of entire communities. The loss of a keystone species results in a range of dramatic cascading effects that alters trophic dynamics, other food-web connections and can cause the extinction of other species in the community(Sony VGN-FZ17L battery).

Sea otters (Enhydra lutris) are commonly cited as an example of a keystone species because they limit the density of sea urchins that feed on kelp. If sea otters are removed from the system, the urchins graze until the kelp beds disappear and this has a dramatic effect on community structure(Sony VGN-FZ17G battery). Hunting of sea otters, for example, is thought to have indirectly led to the extinction of the Steller's Sea Cow (Hydrodamalis gigas). While the keystone species concept has been used extensively as a conservation tool, it has been criticized for being poorly defined from an operational stance(Sony VGN-FZ17 battery). It is very difficult to experimentally determine in each different ecosystem what species may hold a keystone role. Furthermore, food-web theory suggests that keystone species may not be all that common. It is therefore unclear how generally the keystone species model can be applied(Sony VGP-BPS18 battery).

Ecosystem ecology

The concept of the ecosystem was first introduced in 1935 to describe habitats within biomes that form an integrated whole and a dynamically responsive system having both physical and biological complexes(Sony VGP-BPS15 battery). Within an ecosystem there are inseparable ties that link organisms to the physical and biological components of their environment to which they are adapted. Ecosystems are complex adaptive systems where the interaction of life processes form self-organizing patterns across different scales of time and space(Sony VGP-BPS12 battery). This section introduces key areas of ecosystem ecology that are used to inquire, understand and explain observed patterns of biodiversity and ecosystem function across different scales of organization(Sony VGP-BPL12 battery).

Biome

Ecological units of organization are defined through reference to any magnitude of space and time on the planet. Communities of organisms, for example, are somewhat arbitrarily defined, but the processes of life integrate at different levels and organize into more complex wholes(Sony VGP-BPL7 battery). Biomes, for example, are a larger unit of organization that categorize regions of the Earth's ecosystems mainly according to the structure and composition of vegetation. Different researchers have applied different methods to define continental boundaries of biomes dominated by different functional types of vegetative communities that are limited in distribution by climate(Sony VGN-FZ290 battery), precipitation, weather and other environmental variables. Examples of biome names include: tropical rainforest, temperate broadleaf and mixed forests, temperate deciduous forest, taiga,tundra, hot desert, and polar desert. Other researchers have recently started to categorize other types of biomes(Sony VGN-FZ29VN battery), such as the human and oceanic microbiomes. To a microbe, the human body is a habitat and a landscape. The microbiome has been largely discovered through advances in molecular genetics that have revealed a hidden richness of microbial diversity on the planet(Sony VGN-SZ56 battery). The oceanic microbiome plays a significant role in the ecological biogeochemistry of the planet's oceans.

Biosphere

Ecological theory has been used to explain self-emergent regulatory phenomena at the planetary scale. The largest scale of ecological organization is the biosphere: the total sum of ecosystems on the planet(Sony VGN-SZ55 battery). Ecological relations regulate the flux of energy, nutrients, and climate all the way up to the planetary scale. For example, the dynamic history of the planetary CO2 and O2 composition of the atmosphere has been largely determined by the biogenic flux of gases coming from respiration and photosynthesis(Sony VGN-FZ220E battery), with levels fluctuating over time and in relation to the ecology and evolution of plants and animals. When sub-component parts are organized into a whole there are oftentimes emergent properties that describe the nature of the system. This the Gaia hypothesis, and is an example of holism applied in ecological theory(Sony VGN-FZ11Z battery).The ecology of the planet acts as a single regulatory or holistic unit called Gaia. The Gaia hypothesis states that there is an emergent feedback loop generated by the metabolism of living organisms that maintains the temperature of the Earth and atmospheric conditions within a narrow self-regulating range of tolerance(Sony VGN-FZ11M battery).

Relation to evolution

Ecology and evolution are considered sister disciplines of the life sciences. Natural selection, life history, development, adaptation, populations, and inheritance are examples of concepts that thread equally into ecological and evolutionary theory(Sony Vaio VGN-FZ31M battery). Morphological, behavioral and/or genetic traits, for example, can be mapped onto evolutionary trees to study the historical development of a species in relation to their functions and roles in different ecological circumstances(Sony Vaio VGN-FZ31Z battery). In this framework, the analytical tools of ecologists and evolutionists overlap as they organize, classify and investigate life through common systematic principals, such as phylogenetics or the Linnaean system of taxonomy. The two disciplines often appear together(Sony VGN-FZ19VN battery), such as in the title of the journal Trends in Ecology and Evolution. There is no sharp boundary separating ecology from evolution and they differ more in their areas of applied focus. Both disciplines discover and explain emergent and unique properties and processes operating across different spatial or temporal scales of organization(Sony Vaio VGN-FZ38M battery). While the boundary between ecology and evolution is not always clear, it is understood that ecologists study the abiotic and biotic factors that influence the evolutionary process(Sony Vaio VGN-FZ31S battery).